Color separation element and image sensor including the same

ABSTRACT

Provided are a color separation element and an image sensor including the same. The color separation element includes a spacer layer; and a color separation lens array, which includes at least one nano-post arranged in the spacer layer and is configured to form a phase distribution for splitting and focusing incident light according to wavelengths, wherein periodic regions in which color separation lens arrays are repeatedly arranged are provided, and the color separation lens array is configured to interrupt phase distribution at the boundary of the periodic regions.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2019-0133275, filed on Oct. 24,2019, and Korean Patent Application No. 10-2020-0122851, filed on Sep.23, 2020, in the Korean Intellectual Property Office, the disclosures ofwhich are incorporated by reference herein in their entirety.

BACKGROUND 1. Field

The disclosure relates to a color separation element and an image sensorincluding the same.

2. Description of Related Art

Color display devices or color image sensors typically display images ofvarious colors or detect colors of incident light by using colorfilters. For example, a charge-coupled device (CCD) and a complementarymetal-oxide semiconductor (CMOS) may be used as an image sensor.

The number of pixels of an image sensor is gradually increasing, andaccordingly, size reduction of pixels is demanded. For size reduction ofpixels, it is necessary to secure light quantity and to remove noise.

Image sensors typically display images of various colors or detectcolors of incident light by using color filters. However, since a colorfilter absorbs light of colors other than light of a correspondingcolor, light utilization efficiency may be reduced. For example, in caseof using RGB color filters, only one-third of incident light istransmitted therethrough and the remaining two-thirds are absorbed, andthus light use efficiency is only about 33%. In other words, light lossis significant.

Recently, to improve light utilization efficiency of an image sensor, itis being attempted to employ a color separation element instead of acolor filter. A color separation element splits colors of incident lightby using diffraction or refraction characteristics of light that differsdepending on wavelengths, and may adjust directions of light forrespective wavelengths according to refractive indexes and shapes.Colors separated by the color separation element may be delivered tocorresponding pixels, respectively.

SUMMARY

Provided is a color separation element with improved color purity.

Provided is an image sensor including a color separation element withimproved color purity.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments of the disclosure.

According to an aspect of the disclosure, there is provided a colorseparation element includes a spacer layer; and a color separation lensarray, which comprises one or more nano-posts arranged on the spacerlayer, the color separation lens array configured to form a phasedistribution that splits and focuses light incident to the colorseparation lens array based on wavelengths of the light, wherein thecolor separation lens array comprises a plurality of periodic regions inwhich the one or more nano-posts are repeatedly arranged, and the colorseparation lens array is configured to interrupt phase distribution at aboundary between adjacent ones of the plurality of periodic regions.

The plurality of periodic regions may include a first periodic regionand a second periodic region adjacent to each other, and a first phasedistribution formed by a first set of the one or more nano-posts of thecolor separation lens array in the first periodic region and a secondphase distribution formed by a second set of the one or more nano-postsof the color separation lens array in the second periodic region may notoverlap at the boundary between the first periodic region and the secondperiodic region.

The color separation lens array in one periodic region may be configuredto form an asymmetrical phase distribution for each wavelength light ofthe incident light.

The color separation lens array in one periodic region may be configuredto form a non-radial phase distribution for each wavelength light of theincident light.

The plurality of periodic regions may include a first region forfocusing first wavelength light, a second region for focusing secondwavelength light, a third region for focusing third wavelength light,and a fourth region for focusing first wavelength light, the firstregion and the fourth may be located on a diagonal line, and the secondregion and a third region may be located on a diagonal line.

The first wavelength light may include green light, the secondwavelength light may include blue light, and the third wavelength lightmay include red light.

The first wavelength light may have a phase of 2Nπ (N is an integergreater than 0) at the center of the first region and the phase of thefirst wavelength light may decrease in directions toward the outside ofthe periodic region.

The first wavelength light may have a phase of (2N−1)π (N is an integergreater than 0) at the center of the second region, and the firstwavelength light may have a phase of (2N−1)π (N is an integer greaterthan 0) at the center of the third region.

The color separation lens array may be configured to form a continuousphase distribution within each of the plurality of periodic regions.

According to an aspect of another embodiment, an image sensor includesan optical sensor including a plurality of light detecting cells forsensing light; a spacer layer provided in the optical sensor; and acolor separation lens array, which comprises one or more nano-postsarranged on the spacer layer, the color separation lens array configuredto form a phase distribution that splits and focuses light incident tothe color separation lens array based on wavelengths of the light,wherein the color separation lens array comprises a plurality ofperiodic regions in which the one or more nano-posts are repeatedlyarranged, and the color separation lens array is configured to interruptphase distribution at the boundary of the plurality of periodic regions.

The image sensor may further include a color filter between the opticalsensor and the spacer layer.

The image sensor may further include a photographing lens unitconfigured to focus light reflected by an object on a light incidenceside of the color separation lens array and form an optical image.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic block diagram of an image sensor according to anexample embodiment;

FIG. 2 is a schematic view of a color separation element according to anexample embodiment;

FIGS. 3A to 3C are diagrams showing example arrangements of periodicregions of a color separation element according to an exampleembodiment;

FIGS. 4 and 5 are schematic views of an image sensor according to anexample embodiment;

FIG. 6 is a schematic plan view of an optical sensor included in animage sensor according to an example embodiment;

FIG. 7 is a diagram showing an example of a periodic region of a colorseparation element according to an example embodiment;

FIG. 8 is a schematic view of a phase distribution for first wavelengthlight in a periodic region of a color separation element according to anexample embodiment;

FIG. 9 is a schematic view of a phase distribution for second wavelengthlight in a periodic region of a color separation element according to anexample embodiment;

FIG. 10 is a schematic view of a phase distribution for secondwavelength light in a periodic region having a 2×2 arrangement structureof a color separation element according to an example embodiment;

FIGS. 11A and 11B are diagrams showing a phase distribution for bluelight in one periodic region and a phase distribution for blue light ina periodic region having a 3×3 arrangement structure;

FIGS. 12A and 12B are diagrams showing a phase distribution for greenlight in one periodic region and a phase distribution for green light ina periodic region having a 3×3 arrangement structure;

FIGS. 13A and 13B are diagrams showing a phase distribution for redlight in one periodic region and a phase distribution for red light in aperiodic region having a 3×3 arrangement structure;

FIGS. 14 to 17 are diagrams showing nano-post arrangement structures ofa color separation lens array employed in a color separation elementaccording to example embodiments;

FIG. 18A shows a phase distribution for a region corresponding to bluelight in an image sensor according to an example embodiment, and FIG.18B shows that the blue light is focused according to the phasedistribution;

FIG. 19A shows a phase distribution for a region corresponding to greenlight in an image sensor according to an example embodiment, and FIG.19B shows that the green light is focused according to the phasedistribution;

FIG. 20A shows a phase distribution for a region corresponding to redlight in an image sensor according to an example embodiment, and FIG.20B shows that the red light is focused according to the phasedistribution;

FIG. 21 is a diagram showing an example of a cylindrical nano-postemployed in a color separation element of an image sensor according toan example embodiment;

FIGS. 22A to 22H are diagrams showing examples of nano-posts employed ina color separation element of an image sensor according to an exampleembodiment;

FIGS. 23 and 24 are diagrams showing an example in which a color filteris further provided in the image sensor shown in FIGS. 4 and 5 ;

FIG. 25 is a schematic view of an image sensor according to an exampleembodiment;

FIG. 26 is a schematic block diagram of an electronic device includingan image sensor according to example embodiments; and

FIGS. 27 to 37 are diagrams showing examples of electronic devices towhich image sensors according to embodiments are applied.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the exampleembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theexample embodiments are merely described below, by referring to thefigures, to explain aspects. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.Expressions such as “at least one of,” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list.

Hereinafter, a color separation element according to various exampleembodiments and an image sensor including the same will be described indetail with reference to the accompanying drawings. In the drawings,like reference numerals denote like elements, and the size and thicknessof each element may be exaggerated for clarity of explanation. Whilesuch terms as “first,” “second,” etc., may be used to describe variouselements, such elements must not be limited to the above terms. Theabove terms are used only to distinguish one component from another.

An expression used in the singular encompasses the expression of theplural, unless it has a clearly different meaning in the context. Inaddition, unless explicitly described to the contrary, the word“comprise” and variations such as “comprises” or “comprising” will beunderstood to imply the inclusion of stated elements but not theexclusion of any other elements. Also, the size or the thickness of eachcomponent in the drawings may be exaggerated for clarity of description.Also, when it is described that a certain material layer is present on asubstrate or other layer, the material layer may be present in directcontact with the substrate or another layer, and there may be anotherthird layer in between. In addition, the materials constituting layersin the following embodiments are merely examples, and other materialsmay also be used.

In addition, the terms “unit”, “-or”, and “module” described in thespecification mean units for processing at least one function andoperation and may be implemented by hardware components or softwarecomponents and combinations thereof.

The specific implementations described in the example embodiments of thedisclosure are illustrative and do not in any way limit the scope of thedisclosure. For clarity of description, descriptions of related artelectronic configurations, control systems, software, and otherfunctional aspects of such systems may be omitted. Also, connections oflines or connecting members between the components shown in the drawingsare example illustrations of functional connections and/or physical orcircuit connections, which may be replaced with or additionally providedby various functional connections, physical connections, or circuitconnections.

The use of the terms “the” and similar indication words may refer toboth singular and plural.

Operations that constitute a method may be performed in any suitableorder, unless explicitly stated to be done in an order described.Furthermore, the use of all exemplary terms (e.g., etc.) is merelyintended to be illustrative of technical ideas and is not to beconstrued as limiting the scope of the term unless further limited bythe claims.

FIG. 1 is a schematic block diagram of an image sensor according to anexample embodiment.

Referring to FIG. 1 , an image sensor 1000 according to an exampleembodiment may include a pixel array 1100, a timing controller (TC)1010, a row decoder 1020, and an output circuit 1030. The image sensor1000 may further include a processor 1040, which controls the pixelarray 1100, the timing controller 1010, and the output circuit 1030 andprocesses an image signal output through the output circuit 1030. Animage sensor according to an example embodiment may be a charge-coupleddevice (CCD) image sensor or a complementary metal-oxide semiconductor(CMOS) image sensor.

The pixel array 1100 includes a plurality of pixels 2-dimensionallyarranged along a plurality of rows and a plurality of columns. The rowdecoder 1020 selects any one row from among the plurality of rows of thepixel array 1100 in response to a row address signal output from thetiming controller 1010. The output circuit 1030 outputs light detectingsignals column by column from a plurality of pixels arranged along theselected row. To this end, the output circuit 1030 may include a columndecoder and an analog to digital converter (ADC). For example, theoutput circuit 1030 may include a plurality of ADCs arranged forrespective columns between the column decoder and the pixel array 1100.Alternatively, the output circuit 1030 may include one ADC provided atan output terminal of the column decoder. According to exampleembodiments, the timing controller 1010, the row decoder 1020, and theoutput circuit 1030 may be implemented as a single chip or may beimplemented as separate chips. A processor for processing an imagesignal output through the output circuit 1030 may be implemented as asingle chip together with the timing controller 1010, the row decoder1020, and the output circuit 1030.

The pixel array 1100 may include a plurality of pixels for sensing lightof different wavelengths. The plurality of pixels for sensing light ofdifferent wavelengths may be implemented in various arrangements.

FIG. 2 is a schematic view of the structure of a color separationelement 100 according to an example embodiment.

In FIG. 2 , the color separation element 100 includes a spacer layer 120and a color separation lens array 140, which is provided in the spacerlayer 120 and includes a plurality of nano-posts NPs. The plurality ofnano-posts NP may be arranged according to a certain rule. According toan example embodiment, the rule may be a predetermined rule.

Here, the rule is applied to parameters, such as the shape, the size(width and height), the spacing, and the arrangement shape of thenano-posts NP, and the parameters may be determined based on a targetphase distribution TP to be implemented by the nano-posts NPs withrespect to incident light Li. The target phase distribution TP may bedetermined in consideration of target regions R1 and R2 to focus theincident light Li by separating the wavelength of the incident light Li.Although the target phase distribution TP is shown between the colorseparation element 100 and the target regions R1 and R2, it is merelyfor convenience of illustration, and the target phase distribution TPmay refer to a phase distribution of the incident light Li at a locationimmediately after the incident light Li passes through the colorseparation lens array 140. The color separation lens array 140 mayseparate the incident light Li according to respective wavelengths andadjust the phase distribution of light of each wavelength to focus thelight of each wavelength to a certain target region R1 or R2.

The nano-posts NPs may include a material having a refractive indexhigher than that of the surroundings, and the spacer layer 120 mayinclude a material having refractive index lower than that of thenano-posts NPs.

The nano-posts NP may include, for example, at least one of c-Si, p-Si,a-Si, and group III-V compound semiconductors (e.g., GaP, GaN, GaAs,etc.), SiC, TiO₂, SiN. The spacer layer 120 may include any one of glass(e.g., fused silica, BK7, etc.), quartz, polymer (e.g., PMMA, SU-8,etc.) and plastic.

The nano-posts NPs having a refractive index different from that of asurrounding material may change the phase of light passing through thenano-posts NP. This is due to a phase delay caused by the shapedimension of a sub-wavelength of the nano-posts NPs, and the degree ofthe phase delay is determined based on the specific shape dimension andarrangement shape of the nano-posts NPs. The plurality of nano-posts NPsmay achieve various optical functions by appropriately setting thedegree of a phase delay occurring in each of the plurality of nano-postsNPs.

The color separation element 100 is for splitting the incident light Liaccording to wavelengths and focusing the split incident light atdifferent target regions R1 and R2, wherein detailed rules of thenano-posts NPs may be determined according to the target phasedistribution TP for implementing the focusing at desired locations.

The phase of first wavelength light Lλ₁ at a position immediately afterpassing through the color separation element 100 may be 2Nπ (N is aninteger greater than 0) at the center of a position corresponding to afirst region 141 and may be (2N−1)π (N is an integer greater than 0) atthe center of a position corresponding to a second region 142.

The phase of second wavelength light Lλ₂ passed through the colorseparation lens array 140 may be (2M−1)π at the center of the positioncorresponding to the first region 141 and may be 2Mπ at the center ofthe position corresponding to the second region 142. Here, M is aninteger greater than 0.

A first wavelength λ1 and a second wavelength λ2 may be within thevisible ray wavelength band. However, the disclosure is not limitedthereto, and the first wavelength λ1 and the second wavelength λ2 may bewithin various wavelength bands according to arrangement rules of thecolor separation lens array 140. Also, although a case where incidentlight is split into light beams of two wavelengths and focused is shown,the disclosure is not limited thereto, and incident light may be splitinto three or more directions according to wavelengths and focused.

The color separation lens array 140 may include the first region 141 andthe second region 142, each of which includes one or more nano-postsNPs. The first region 141 and the second region 142 may be respectivelyarranged to face the first target region R1 and the second target regionR2 on the one-on-one basis. Although FIG. 1 shows that three nano-postsNPs are arranged in each of the first region 141 and the second region142, it is merely an example. Also, although FIG. 1 shows that thenano-posts NPs are entirely located in any one of the first region 141and the second region 142, the disclosure is not limited thereto, andsome of the nano-posts NPs may be arranged at the boundary between thefirst region 141 and the second region 142. For example, the colorseparation lens array 140 may be configured to have a first phasedistribution with respect to the first wavelength light Lλ₁ of theincident light Li and to focus the first wavelength light Lλ₁ to thefirst target region R1. Also, the color separation lens array 140 may beconfigured to have a second phase distribution with respect to thesecond wavelength light Lλ₂ of the incident light Li and to focus thesecond wavelength light Lλ₂ to the second target region R2.

For example, FIGS. 3A to 3C show examples of various pixel arrangementsof the pixel array 1100 of the image sensor 1000.

FIG. 3A shows a so-called Bayer pattern. The color separation element100 may include periodic regions 150 in which elements of colorseparation lens array 140 are repeatedly arranged. The periodic region150 may correspond to a repeated arrangement of a plurality of pixels.The periodic regions 150 may be repetitive regions of a minimum unit forsplitting the incident light Li by wavelengths. The periodic regions 150may be 2-dimensionally and repeatedly arranged. For example, theperiodic region 150 may correspond to a 2×2 pixel region. A pixel PX mayrepresent a unit capable of sensing light by wavelengths andelectrically processing light amounts. The periodic region 150 may be,for example, divided into four regions and may be configured to splitthe incident light Li into green light G, blue light B, and red light R.According to an example embodiment, the periodic region 150 that isdivided into four regions and shown in FIG. 3A is merely for convenienceof explanation, and a color separation lens array in the periodic region150 is not divided into four pieces. The color separation element 100may be applied to an image sensor, and the image sensor may include, forexample, a blue pixel B, a green pixel G, a red pixel R, and a greenpixel G. Pixel arrangement as described above may be 2-dimensionallyrepeated in a first direction (X direction) and a second direction (Ydirection). In other words, in a unit pixel in the form of a 2×2 array,two green pixels G are arranged in one diagonal direction, and one bluepixel B and one red pixel R are arranged in the other diagonaldirection. In terms of the overall pixel arrangement, first rows inwhich a plurality of green pixels G and a plurality of blue pixels B arealternately arranged in the first direction and second rows in which aplurality of red pixels R and a plurality of green pixels G arealternately arranged in the first direction are repeatedly arranged inthe second direction. Here, the same reference numerals are used forpixels and light of respective wavelengths.

The arrangement scheme of the pixel array 1100 of the image sensor 1000is not limited to the Bayer pattern, and various arrangement schemesother than the Bayer pattern may be applied. For example, referring toFIG. 3B, a CYGM scheme in which a magenta pixel M, a cyan pixel C, ayellow pixel Y, and a green pixel G constitute one unit pixel may alsobe applied. Also, referring to FIG. 3C, an RGBW scheme in which a greenpixel G, a red pixel R, a blue pixel B, and a white pixel W constituteone unit pixel may also be applied. Also, although not shown, a unitpixel may be in the form of a 3×2 array. Also, pixels of the pixel array1100 may be arranged in various ways according to the colorcharacteristics of the image sensor 1000. Hereinafter, for convenienceof explanation, it is described below that the pixel array 1100 of theimage sensor 1000 has a Bayer pattern. However, the principles of theexample embodiments described below may be applied to pixel arrangementsother than the Bayer pattern.

The color separation element described above may be applied to variousimage sensors. Hereinafter, an example embodiment in which the colorseparation element is applied to an image sensor will be described.

FIGS. 4 and 5 are diagrams showing different cross-sections of theschematic structure of an image sensor according to an exampleembodiment. Referring to the pixel arrangement structure of FIG. 3A,FIG. 4 may be a cross-sectional view obtained along a line I-I, and FIG.5 may be a cross-sectional view obtained along a line II-II.

An image sensor 300 may include an optical sensor 310, which includes aplurality of light detecting cells 311, 312, 313, and 314 for detectinglight, and a color separation element 360 provided on the optical sensor310.

The optical sensor 310 may include a first light detecting cell 311, asecond light detecting cell 312, a third light detecting cell 313, and afourth light detecting cell 314 for converting light into electricalsignals. The first light detecting cell 311, the second light detectingcell 312, the third light detecting cell 313, and the fourth lightdetecting cell 314 may be alternately arranged. As shown in FIG. 4 ,first light detecting cells 311 and second light detecting cells 312 maybe alternately arranged in the first direction (the X direction), and,as shown in FIG. 5 , third light detecting cells 313 and fourth lightdetecting cells 314 may be alternately arranged in the first direction(the X direction) in a different cross-section in the Y direction, thatis, a cross-section II-II. This regional division is for sensingincident light pixel-by-pixel. For example, the first light detectingcell 311 may sense light of a first wavelength corresponding to a firstpixel, the second light detecting cell 312 may sense light of a secondwavelength corresponding to a second pixel, the third light detectingcell 313 may sense light of a third wavelength corresponding to a thirdpixel, and the fourth light detecting cell 314 may sense light of afourth wavelength corresponding to a fourth pixel. The first pixel, thesecond pixel, the third pixel, and the fourth pixel may respectively bea green pixel G, a blue pixel B, a red pixel R, and a green pixel G, butare not limited thereto. Although not shown, isolation films may befurther provided at the boundaries between pixels.

The color separation element 360 includes a color separation lens array340 in which a plurality of nano-posts NPs are arranged according to acertain rule. The color separation lens array 340 may be supported by aspacer layer 320. The spacer layer 320 may be provided to maintain acertain distance between the optical sensor 310 and the plurality ofnano-posts NPs. Also, although not shown, a dielectric layer forprotecting the plurality of nano-posts NPs may be further provided. Thedielectric layer may have a height same as or greater than that of thenano-post NP and may be provided around the nano-post NP. The dielectriclayer may include a dielectric material having a refractive index lowerthan that of a material constituting the nano-posts NP.

The shape, the size, and the arrangement of the plurality of nano-postsNPs may be configured to form a phase distribution for focusing lightbeams of different wavelengths to the first light detecting cell 311 andthe second light detecting cell 312 adjacent to each other,respectively. Also, the shape, the size, and the arrangement of theplurality of nano-posts NPs may be configured to form a phasedistribution for focusing light beams of different wavelengths to thethird light detecting cell 313 and the first light detecting cell 311adjacent to each other, respectively.

The color separation lens array 340 may be divided into a plurality ofregions 341, 342, 343, and 344 that face the plurality of lightdetecting cells 311, 312, 313, and 314, respectively. One or morenano-posts NPs may be arranged in each of the plurality of regions 341,342, 343, and 344, and at least one of the shape, the size, and thearrangement of the nano-posts NPs may vary from one region to another.

As shown in FIGS. 4 and 5 , the first region 341 and the first lightdetecting cell 311 may be arranged to correspond to each other, thesecond region 342 and the second light detecting cell 312 may bearranged to correspond to each other, the third region 343 and the thirdlight detecting cell 313 may be arranged to correspond to each other,and the fourth region 344 and the fourth light detecting cell 314 may bearranged to correspond to each other.

The color separation lens array 340 may split incident light, such thatlight of the first wavelength is focused to the first light detectingcell 311, light of the second wavelength is focused to the second lightdetecting cell 312, light of the third wavelength is focused to thethird light detecting cell 313, and light of the first wavelength isfocused to the fourth light detecting cell 314. Also, the colorseparation lens array 340 may allow the phase of light of eachwavelength to be continuously distributed within the periodic region 150of pixels and block phase distribution at the boundary of the periodicregion 150. As a result, light of different wavelengths may be preventedfrom being mixed at the boundary between neighboring periodic regions150, thereby improving color purity. Detailed description thereof willbe given below.

FIG. 6 is a plan view of the light sensor 310. Referring to FIG. 6 ,first rows in which first light detecting cells 311 and second lightdetecting cells 312 are alternately arranged and second rows in whichthe third light detecting cells 313 and the fourth light detecting cells314 are alternately arranged may be repeated arranged. In the lightsensor 310, a plurality of first light detecting cells 311, a pluralityof second light detecting cells 312, a plurality of third lightdetecting cells 313, and a plurality of fourth light detecting cells 314may be 2-dimensionally arranged in the first direction (X direction) andthe second direction (Y direction). For example, referring to FIGS. 3Aand 6 , the first light detecting cell 311 and the fourth lightdetecting cell 314 may correspond to the green pixel G, the second lightdetecting cell 312 may correspond to the blue pixel B, and the thirdlight detecting cell 313 may correspond to the red pixel R.

The illustrated arrangement rule of the color separation lens array 340is an example for implementing a target phase distribution for splittingincident light, such that light of a first wavelength is focused to thefirst light detecting cell 311 and the fourth light detecting cell 314,light of a second wavelength is condensed to the second light detectingcell 312, and light of a third wavelength is condensed to the thirdlight detecting cell 313, but is not limited thereto.

The shapes, the sizes, and the arrangements of the nano-posts NParranged in the first region 341, the second region 342, the thirdregion 343, and the fourth region 344 may be determined, such that aphase inducing light of the first wavelength to be focused at the firstlight detecting cell 311 and the fourth light detecting cell 314 at aposition past the color separation lens array 340 and preventing lightof the first wavelength from being focused at the second light detectingcell 312 and the third light detecting cell 313 adjacent to the firstlight detecting cell 311 and the fourth light detecting cell 314 isformed at a position immediately after passing through the colorseparation lens array 340.

Similarly, the shapes, the sizes, and the arrangements of the nano-postsNP arranged in the first region 341, the second region 342, the thirdregion 343, and the fourth region 344 may be determined, such that aphase inducing light of the second wavelength to be focused at thesecond light detecting cell 312 and preventing light of the secondwavelength from being focused at the first light detecting cell 311, thethird light detecting cell 313, and the fourth light detecting cell 314adjacent to the second light detecting cell 312 is formed at a positionimmediately after passing through the color separation lens array 340.

Similarly, the shapes, the sizes, and the arrangements of the nano-postsNP arranged in the first region 341, the second region 342, the thirdregion 343, and the fourth region 344 may be determined, such that aphase inducing light of the third wavelength to be focused at the thirdlight detecting cell 313 and preventing light of the third wavelengthfrom being focused at the first light detecting cell 311, the secondlight detecting cell 312, and the fourth light detecting cell 314adjacent to the third light detecting cell 313 is formed at a positionimmediately after passing through the color separation lens array 340.

The shapes, the sizes, and the arrangements of the nano-posts NP thatsatisfy all of these conditions may be determined, and the colorseparation lens array 340 having the same may allow light to have thefollowing target phase distribution immediately after passing throughthe same. At a position immediately after passing through the colorseparation lens array 340, that is, on the bottom surface of the colorseparation lens array 340 or the top surface of the spacer layer 320,the phase of the light of the first wavelength may be a distributionthat exhibits a phase difference of 2Nπ at the center portion of thefirst region 341 corresponding to the first light detecting cell 311 andthe center portion of the fourth region 344 corresponding to the fourthlight detecting cell 314 and exhibits a phase difference of (2N−1)π atthe center portion of the second region 342 corresponding to the secondlight detecting cell 312 and the center portion of the third region 343corresponding to the third light detecting cell 313. Here, N is aninteger greater than 0.

In other words, at the position immediately after passing through thecolor separation lens array 340, the phase of the light of the firstwavelength may become maximum at the center of the first region 341 andthe center of the fourth region 344, decrease in concentric-circularshape as distances from the center of the first region 341 and thecenter of the fourth region 344 increase, and become minimum at thecenter of the second region 342 and the center of the third region 343.In the example embodiment, a plurality of first regions 341 are providedadjacent to one another, and a phase difference of 2Nπ may be exhibitedat the center of every first region 341. A plurality of fourth regions344 are provided adjacent to one another, and a phase difference of 2Nπmay be exhibited at the center of every fourth region 344. For example,when N=1, at the position after passing through the color separationlens array 340, the phase of the light of the first wavelength may be 2πat the center of the first region 341 and the center of the fourthregion 344 and may be π at the center of the second region 342 and thecenter of the third region 343. Here, the phase may refer to a relativephase value after light passed through the nano-post NP with respect toa phase immediately before passing through the nano-post NP.

Also, at the position after passing through the color separation lensarray 340, the phase of the light of the second wavelength may be 2Mπ atthe center of the second region 342 corresponding to the second lightdetecting cell 312 and may be (2M−1)π at the center of the first region341 corresponding to the first light detecting cell 311, at the centerof the fourth region 344 corresponding to the fourth light detectingcell 314, and at the center of the third region 343 corresponding to thethird light detecting cell 313. Here, M is an integer greater than 0. Inother words, at the position immediately after passing through the colorseparation lens array 340, the phase of the light of the secondwavelength may become maximum at the center of the second region 342,decrease in concentric-circular shape as a distance from the center ofthe second region 342 increases, and become minimum locally at thecenters of the first region 341, the fourth region 344, and the thirdregion 343. For example, when M=1, at the position after passing throughthe color separation lens array 340, the phase of the light of thesecond wavelength may be 2π at the center of the second region 342, maybe π at the center of the first region 341 and the center of the fourthregion 344, and may be from about 0.2π to about 0.7π at the center ofthe third region 343.

Also, similarly, at the position after passing through the colorseparation lens array 340, the phase of the light of the thirdwavelength may be 2Lπ at the center of the third region 34 correspondingto the third light detecting cell 313, may be (2L−1)π at the center ofthe first region 341 corresponding to the first light detecting cell311, at the center of the fourth region 344 corresponding to the fourthlight detecting cell 314, and at the center of the second region 342corresponding to the second light detecting cell 312, and may be greaterthan (2L−2)π and smaller than (2L−1)π at the center of the second region342 corresponding to the second light detecting cell 312. Here, L is aninteger greater than 0. In other words, at the position immediatelyafter passing through the color separation lens array 340, the phase ofthe light of the third wavelength may become maximum at the center ofthe third region 343, decrease in concentric-circular shape as adistance from the center of the third region 343 increases, and becomeminimum locally at the centers of the first region 341, the fourthregion 344, and the second region 342. For example, when L=1, at theposition after passing through the color separation lens array 340, thephase of the light of the third wavelength may be 2π at the center ofthe third region 343, may be π at the center of the first region 341 andthe center of the fourth region 344, and may be from about 0.2π to about0.7π at the center of the second region 342. Here, the above-statedtarget phase distribution refers to a phase distribution of light at theposition immediately after passing through the color separation lensarray 340. When light having such a phase distribution reaches the firstlight detecting cell 311, the second light detecting cell 312, the thirdlight detecting cell 313, and the fourth light detecting cell 314 fromthe color separation lens array 340, light having wavelengthscorresponding to respective positions may be focused. Then, light thathas passed through the color separation lens array 340 may be divergedaccording to the wavelengths, travel in different directions, and befocused.

When light of such a phase distribution travels toward the plurality oflight detecting cells 311, 312, 313, and 314, a certain propagationdistance condition may be set, such that light of the first wavelengthis diverged toward the first light detecting cell 311 and the fourthlight detecting cell 314, light of the second wavelength is divergedtoward the second light detecting cell 312, and light of the thirdwavelength is diverged toward the third light detecting cell 313 to befocused at corresponding cells. Accordingly, a thickness h of the spacerlayer 320 may be determined. The thickness h of the spacer layer 320 maydepend on a wavelength λ of light to be diverged or a pixel size. Thethickness h of the spacer layer 320 may be greater than the wavelength λof light to be diverged. For example, the thickness h of the spacerlayer 320 may be greater than the center wavelength λ of the visible raywavelength band. The thickness h of the spacer layer 320 may be 1λ orgreater. The thickness h of the spacer layer 320 may depend on anarrangement period p of light detecting cells. The period p may beexpressed as a distance between centers of light detecting cellsadjacent to each other. The thickness h of the spacer layer 320 may havea range from 1 p to 3 p. The thickness h of the spacer layer 320 mayhave a range from about 500 nm to about 5 μm, for example.

FIG. 7 is a schematic view of the periodic region 150 of a colorseparation lens array. The periodic region 150 may include, for example,a first region 151, a second region 152, a third region 153, and afourth region 154. The first region 151 may be a pixel regioncorresponding to first wavelength light (e.g., green light), the secondregion 152 may be a pixel region corresponding to second wavelengthlight (e.g., blue light), the third region 153 may be a pixel regioncorresponding to third wavelength light (e.g., red light), and thefourth region 154 may be a pixel region corresponding to fourthwavelength light (e.g., green light). For example, the first wavelengthlight may include green light, the second wavelength light may includeblue light, the third wavelength light may include red light, and thefourth wavelength light may include green light. The first region 151and the fourth region 154 may be positioned on a diagonal line, and thesecond region 152 and the third region 153 may be positioned on adiagonal line.

The nano-posts NPs are arranged in the periodic region 150, and phasedistribution of light passing through the periodic region 150 may becontrolled by the nano-posts NPs. A phase distribution region may be aregion immediately after passing through the color separation lens array340. The color separation lens array 340 may adjust the phasedistribution of any one wavelength light in a region of thecorresponding wavelength light, and may adjust the phase distribution tobe interrupted at a boundary 165 of the periodic region 150.

According to an example embodiment, a rule in which the nano-posts NPsare arranged in the first region 151, a rule in which the nano-posts NPsare arranged in the second region 152, a rule in which the nano-postsNPs are arranged in the third region 153, and a rule in which thenano-posts NPs are arranged in the fourth region 154 may be differentfrom one another. Alternatively, when the first region 151 and thefourth region 154 are regions for the green light G, the nano-posts NPin the first region 151 and the fourth region 154 may be arrangedorigin-symmetrically. However, the arrangement of the nano-posts NPs isnot limited thereto, and various arrangements may be applied. Thenano-posts NP may have a shape dimension of the sub-wavelength. Here,the sub-wavelength means a wavelength smaller than a wavelength band tosplit. The nano-posts NP may have, for example, a shape dimensionsmaller than the shortest wavelength from among a first wavelength, asecond wavelength, and a third wavelength.

According to an example embodiment, a first nano-post NP may be arrangedin a center 151C of the first region 151, a second nano-post NP may bearranged in a center 152C of the second region 152, a third nano-post NPmay be arranged in a center 153C of the third region 153, and a fourthnano-post NP may be arranged in a center 154C of the first region 154.

FIG. 8 is a diagram showing, for example, a phase distribution 160 offirst wavelength light of light passing through the periodic region 150.Here, the periodic region 150 represents a periodic region in which thenano-posts NPs are arranged and may be used to indicate a pixel regioncorresponding thereto. Furthermore, the periodic region 150 may indicatea corresponding region of an optical sensor as a target region forfocusing light that has passed through the color separation lens array.The first wavelength light has the phase distribution 160 in which thephase gradually decreases in outward directions from a center 151C ofthe first region 151, wherein the phase distribution may be interruptedat the boundary 165 of the periodic region 150. The phase at the center151C of the first region 151 may be 2Nπ (N is an integer greater than0), and the phase may decrease in outward directions. For example, thephase at the center 151C of the first region 151 may be 2Nπ (N is aninteger greater than 0), and the phases at centers 152C and 153C of thesecond region 152 and the third region 153 adjacent thereto may each be2(N−1)π (n is an integer greater than 0). However, the disclosure is notlimited thereto, and various modifications may be made therein. Thephase may be continuously changed in the periodic region 150, and thephase may be interrupted at the boundary 165 of the periodic region 150.In an example embodiment, the color separation lens array 340 may beconfigured to distribute phases asymmetrically and non-radially withrespect to the center 151C of the first region 151.

FIG. 9 is a diagram showing, for example, a phase distribution 161 ofsecond wavelength light of light passing through the periodic region150. The second wavelength light has the phase distribution 161 in whichthe phase gradually decreases in outward directions from a center 152Cof the second region 152, wherein the phase distribution may beinterrupted at the boundary 165 of the periodic region 150. The phase atthe center 152C of the second region 152 may be 2Mπ (M is an integergreater than 0), and the phases at centers 151C and 154C of the firstregion 151 and the fourth region 154 adjacent thereto may each be2(M−1)π (M is an integer greater than 0). However, the disclosure is notlimited thereto, and various modifications may be made therein. Thephase may be continuously changed in the periodic region 150, and thephase may be interrupted at the boundary 165 of the periodic region 150.In an example embodiment, the color separation lens array 140 may beconfigured to distribute phases asymmetrically and non-radially withrespect to the center 152C of the second region 152.

According to another example embodiment, the third wavelength light mayhave the phase distribution in which the phase gradually decreases inoutward directions from a center 153C of the third region 153, whereinthe phase distribution may be interrupted at the boundary 165 of theperiodic region 150. The phase at the center 153C of the third region153 may be 2Lπ (L is an integer greater than 0), and the phases atcenters 151C and 154C of the first region 151 and the fourth region 154adjacent thereto may each be 2(L−1)π (L is an integer greater than 0).Also, the first wavelength light has the phase distribution in which thephase gradually decreases in outward directions from a center 154C ofthe fourth region 154, wherein the phase distribution may be interruptedat the boundary 165 of the periodic region 150.

FIG. 10 is a diagram showing an example in which a plurality of periodicregions 150 are arranged and showing the phase distribution 161 forsecond wavelength light in each periodic region 150. Referring to FIG.10 , the phase of the second wavelength light is continuouslydistributed in each periodic region 150 and is interrupted at theboundary of the periodic region 150. At the boundary 165 of twoneighboring periodic regions, phase distributions formed by colorseparation lens arrays in the respective periodic regions may notoverlap each other. Although FIG. 10 shows the phase distribution forthe second wavelength light, phases may be distributed on the sameprinciple for the first wavelength light, the third wavelength light,and the fourth wavelength light.

FIG. 11A shows a phase distribution for the blue light B in one periodicregion, wherein the phase of which is, for example, 2π at the center ofthe blue light region B, the phase decreases in directions toward theoutside, and the phase distribution is interrupted at the boundary ofthe periodic region. For convenience of explanation, the same referencenumeral will be used for blue light and a blue light region. Theinterruption of the phase distribution may indicate that the phase isnot distributed at the boundary of the periodic region.

FIG. 11B shows that periodic distributions are arranged 3 by 3 and showsphase distribution of the blue light B in each periodic region. It isshown that the phase distribution of the blue light B is continuouslychanged in each periodic region, and the phase distribution of the bluelight B is interrupted at the boundary of each periodic region.Therefore, mixing of different color lights in neighboring periodicregions may be reduced.

FIG. 12A shows a phase distribution for the green light G in oneperiodic region, wherein the phase of which is, for example, 2π at thecenter of the green light region G, the phase decreases in directionstoward the outside, and the phase distribution is interrupted at theboundary of the periodic region.

FIG. 12B shows that periodic distributions are arranged 3 by 3 and showsphase distribution of the green light G in each periodic region. It isshown that the phase distribution of the green light G is interrupted atthe boundary of each periodic region.

FIG. 13A shows a phase distribution for the red light R in one periodicregion, wherein the phase of which is, for example, 2π at the center ofthe red light region R, the phase decreases in directions toward theoutside, and the phase distribution is interrupted at the boundary ofthe periodic region.

FIG. 13B shows that periodic distributions are arranged 3 by 3 and showsphase distribution of the red light R in each periodic region. It isshown that the phase distribution of the red light R is interrupted atthe boundary of each periodic region.

According to an example embodiment, the color separation lens array 340may form a phase distribution for splitting light of two or moredifferent wavelengths included in incident light in different directionsand focusing the same. For example, the shape, the size, and thearrangement of the nano-posts NPs may be configured, such that firstwavelength light included in incident light has a first phasedistribution, second wavelength light has a second phase distribution,and third wavelength light has a third phase distribution.

FIG. 14 is a diagram showing an example of an arrangement of thenano-posts NPs in the periodic region 150.

The periodic region 150 of the color separation lens array 340 mayinclude, for example, four pixels PX in a form corresponding to thepixel arrangement of the Bayer pattern and may include four regionsincluding a region G corresponding to a green pixel, a region Bcorresponding to a blue pixel, a region G corresponding to a greenpixel, and a region R corresponding to a red pixel.

Each region may be divided into a plurality of sub-regions, and thenano-posts NPs may be arranged in the sub-regions. Here, ninesub-regions may be provided in each pixel PX, and the nano-posts NP maybe arranged in the sub-regions.

FIG. 15 is a diagram showing another example of nano-post arrangement ofa color separation lens array.

The periodic region 150 of the color separation lens array 340 includesfour pixels PX in a form corresponding to the pixel arrangement of theBayer pattern shown in FIG. 3A. Each pixel PX may be divided into aplurality of sub-regions, and the nano-posts NPs may be arranged atpoints where the boundaries of the sub-regions intersect. In FIG. 15 ,the number of sub-regions is shown as 4.

FIG. 16 is a diagram showing another example of nano-post arrangement ofa color separation lens array.

The periodic region 150 of the color separation lens array 340 includesfour pixels PX in a form corresponding to the pixel arrangement of theBayer pattern shown in FIG. 3A. Each pixel PX may be divided into aplurality of sub-regions, and the nano-posts NPs may be arranged atpoints where the boundaries of the sub-regions intersect. In FIG. 16 ,the number of sub-regions is shown as 9.

FIG. 17 is a diagram showing another example of nano-post arrangement ofa color separation lens array.

The periodic region 150 of the color separation lens array 340 includesfour pixels PX in a form corresponding to the pixel arrangement of theBayer pattern shown in FIG. 3A. Each pixel PX may be divided into aplurality of sub-regions, and the nano-posts NPs may be arranged atpoints where the boundaries of the sub-regions intersect. In FIG. 17 ,the number of sub-regions is shown as 25.

FIG. 18A shows a phase distribution for a region corresponding to theblue light B in an image sensor according to an example embodiment, andFIG. 18B shows that the blue light B is focused according to the phasedistribution.

FIG. 19A shows a phase distribution for a region corresponding to thegreen light G in an image sensor according to an example embodiment, andFIG. 19B shows that the green light G is focused according to the phasedistribution.

FIG. 20A shows a phase distribution for a region corresponding to thered light R in an image sensor according to an example embodiment, andFIG. 20B shows that the red light R is focused according to the phasedistribution.

FIG. 21 is a perspective view of an example form of a nano-post that maybe employed in the color separation lens array 340 of an image sensoraccording to an embodiment. Referring to FIG. 21 , the nano-post mayhave a cylindrical shape having a diameter D and a height H. At leastone of the diameter D and the height H may be a sub-wavelength. Thediameter D may vary according to a position at which the nano-post isplaced.

The nano-post may be formed as a column having various othercross-sectional shapes. FIGS. 22A to 22H are plan views of example formsof a nano-post that may be employed in the color separation lens array340 of an image sensor according to an example embodiment.

As shown in FIG. 22A, the cross-sectional shape of the nano-post may bea circular ring-like shape having an outer diameter D and an innerdiameter Di. A width w of the ring may be a sub-wavelength.

As shown in FIG. 22B, the cross-sectional shape of a nano-post may be anelliptical shape in which a length Dx of the major axis in a firstdirection (X direction) and a length Dy of the minor axis in a seconddirection (Y direction) are different from each other. Such a shape maybe employed, for example, in the first region 151 and the fourth region154 corresponding to green pixels, as shown in FIG. 7 .

As shown in FIGS. 22C, 22D, and 22F, the cross-sectional shape of anano-post may be a square shape, a square ring-like shape, or across-like shape.

As shown in FIGS. 22E and 22G, the cross-sectional shape of a nano-postmay be a rectangular shape or a cross-like shape in which a length Dx inthe first direction (X direction) and a length Dy in the seconddirection (Y direction) are different from each other. Such a shape maybe employed, for example, in the first region 151 and the fourth region154 corresponding to green pixels.

Also, as shown in FIG. 22H, the cross-sectional shape of a nano-post maybe a shape having a plurality of concave arcs.

FIGS. 23 and 24 are schematic views of the structure of an image sensoraccording to another example embodiment. FIG. 23 is a cross-sectionalview obtained along a line I-I of FIG. 3A, and FIG. 24 is across-sectional view obtained along a line II-II of FIG. 3A.

An image sensor 301 according to the example embodiment is an example ofthe image sensor 300 shown in FIGS. 4 and 5 further including a colorfilter 305. The color filter 305 may be further provided between theoptical sensor 310 and the color separation element 360.

The color filter 305 may include a filter having a shape correspondingto the pixel arrangement of the Bayer pattern. For example, the colorfilter 305 may include a first color filter CF1, a second color filterCF2, and a third color filter CF3.

Since the color separation element 360 splits and focuses light ofdifferent wavelengths to the plurality of light detecting cells 311,312, 313, and 314, the color filter 305 is not a necessary component.However, by additionally providing the color filter 305, the colorpurity may be further improved, and, in this case, an amount of incidentlight for each color may be reduced.

A dielectric layer 330 may be further provided on the color separationlens array 340. The dielectric layer 330 may be provided to completelycover a space between nano-posts NP adjacent to one another and the topsurfaces of the nano-posts NP. The dielectric layer 330 may include amaterial having a refractive index lower than that of the nano-post NP.For example, the dielectric layer 330 may include the same material asthe spacer layer 320.

The image sensor according to the above-described example embodimentsmay be employed in various image sensors, such as cameras or electronicdevices. Such an electronic device may be, for example, a smart phone, amobile phone, a mobile phone, a personal digital assistant (PDA), alaptop computer, a PC, various portable devices, and other mobile ornon-mobile computing devices, but is not limited thereto.

FIG. 25 is a block diagram showing a schematic configuration of an imagesensor according to an example embodiment.

The image sensor 1200 may include a photographing lens unit 1300 forfocusing light reflected by an object OBJ and forms an optical image andan image sensor 1400 for converting the optical image formed by thephotographing lens unit 1300 into electric signals. An infrared rayscreening filter may be further provided between the image sensor 1400and the photographing lens unit 1300.

As the image sensor 1400, the image sensor described above withreference to FIGS. 1 to 24 may be employed. The image sensor 1200 alsoincludes an image processor 1600 that processes electrical signals fromthe image sensor 1400 into image signals. The image processor 1600 formsan image by performing operations, such as noise removal and colorinterpolation, on signals for each color sensed by the image sensor1400. Also, the image sensor 1200 may further include a display 1700 fordisplaying an image formed by the image processor 1600 and a memory 1800for storing image data formed by the image processor 1600.

FIG. 26 is a schematic block diagram of an electronic device includingan image sensor according to example embodiments. The electronic deviceincludes an image sensor 1000, a processor 2200, a memory 2300, adisplay 2400, and a bus 2500. The image sensor 1000 obtains imageinformation regarding an outside target object under the control of theprocessor 2200 and provides the image information to the processor 2200.The processor 2200 may store image information provided from the imagesensor 1000 in the memory 2300 through the bus 2500. The processor 2200may also output image information stored in the memory 2300 to thedisplay 2400 and display the image information to a user. Also, asdescribed above, the processor 2200 may perform various image processingon image information provided from the image sensor 1000.

FIGS. 27 to 37 are diagrams showing examples of various multimediadevices, which are electronic devices to which image sensors accordingto example embodiments are applied.

Image sensors according to example embodiments may be applied to variousmultimedia devices having an image capturing function. For example, theimage sensor may be applied to a camera 2000 as shown in FIG. 27 . Thecamera 2000 may be a digital camera or a digital camcorder.

Referring to FIG. 28 , the camera 2000 may include an image capturingunit 2100, the image sensor 1000, and the processor 2200.

The image capturing unit 2100 forms an optical image by focusing lightreflected from a target object OBJ. The image capturing unit 2100 mayinclude an object lens 2010, a lens driver 2120, an aperture 2130, andan aperture driver 2140. Although only one lens element isrepresentatively shown in FIG. 28 for convenience of illustration, theobject lens 2010 may actually include a plurality of lens elementshaving different sizes and shapes. The lens driver 2120 may communicatewith the processor 2200 for information regarding focus detection andmay adjust the position of the object lens 2010 according to a controlsignal provided from the processor 2200. The lens driver 2120 may movethe object lens 2010 to adjust a distance between the object lens 2010and the target object OBJ or adjust the positions of individual lenselements (not shown) in the object lens 2010. The focus on the targetobject OBJ may be adjusted as the lens driver 2120 drives the objectlens 2010. The camera 2000 may have an auto focus function.

Also, the lens driver 2120 may communicate with the processor 2200 forinformation regarding an amount of light and may adjust the aperture2130 according to a control signal provided from the processor 2200. Forexample, the aperture driver 2140 may increase or decrease the openingof the aperture 2130 and adjust the opening time of the aperture 2130according to an amount of light entering the camera 2000 through theobject lens 2010.

The image sensor 1000 may generate an electrical image signal based onthe intensity of incident light. The image sensor 1000 may include thepixel array 1100, the timing controller 1010, and the output circuit1030. Although not shown in FIG. 28 , the image sensor 1000 may furtherinclude the row decoder shown in FIG. 1 . Light transmitted through theobject lens 2010 and aperture 2130 may form an image of the targetobject OBJ on a light-receiving surface of the pixel array 1100. Thepixel array 1100 may be a CCD or CMOS that converts optical signals intoelectrical signals. The pixel array 1100 may include additional pixelsfor performing an AF function or a distance measuring function. Also,the pixel array 1100 may include a color separation lens array asdescribed above.

The processor 2200 may control the overall operation of the camera 2000and may have an image processing function. For example, the processor2200 may provide control signals to the lens driver 2120, the aperturedriver 2140, and the timing controller 1010 for the operations of therespective components.

Also, an image sensor according to example embodiments may be applied toa mobile phone or smart phone 3000 as shown in FIG. 29 and may beapplied to a tablet PC or smart tablet 3100 as shown in FIG. 30 . Also,an image sensor according to example embodiments may be applied to alaptop computer 3200 as shown in FIG. 31 and may be applied to a TV or asmart TV 3300 as shown in FIG. 32 .

For example, the smart phone 3000 or the smart tablet 3100 may include aplurality of high resolution cameras each equipped with a highresolution image sensor. By using high-resolution cameras, depthinformation regarding target objects in an image may be extracted,selective focusing of an image may be adjusted, or target objects in animage may be automatically identified.

Also, an image sensor according to example embodiments may be applied toa smart refrigerator 3400 shown in FIG. 33 , a security camera 3500shown in FIG. 34 , a robot 3600 shown in FIG. 35 , and a medical camera3700 shown in FIG. 36 . For example, the smart refrigerator 3400 mayautomatically recognize food therein by using an image sensor and informa user of information like the existence of a particular food, a type offood stocked or released through a smart phone. The security camera 3500may provide an ultra-high resolution image and may use a highsensitivity to recognize an object or a person in an image even in adark environment. The robot 3600 may be deployed to a disaster site oran industrial site that a person is unable to directly access andprovide a high-resolution image. The medical camera 3700 may providehigh-resolution images for a diagnosis or a surgery and may dynamicallyadjust the field of view.

Also, the image sensor may be applied to a vehicle 3800 as shown in FIG.37 . The vehicle 3800 may include a plurality of vehicle cameras 3810,3820, 3830, and 3840 arranged at various positions. The vehicle camera3810, 3820, 3830, and 3840 may each include an image sensor according toan example embodiment. The vehicle 3800 may provide various informationregarding the inside or around the vehicle 3800 to a driver by using theplurality of vehicle cameras 3810, 3820, 3830, and 3840 and mayautomatically recognize objects or people in an image and provideinformation needed for autonomous driving.

In a color separation element according to an example embodiment, acolor separation lens array allows phases to be distributed within aperiodic region and to be interrupted at the boundary of the periodicregion, thereby reducing mixture of colors from neighboring regions. Asa result, color purity may be improved.

An image sensor according to an example embodiment may improve imagequality by improving color purity.

It should be understood that example embodiments described herein shouldbe considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments. While one or more example embodimentshave been described with reference to the figures, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeas defined by the following claims.

What is claimed is:
 1. A color separation element comprising: a spacer layer; and a color separation lens array, which comprises one or more nano-posts arranged on the spacer layer, the color separation lens array configured to form a phase distribution that splits and focuses light incident to the color separation lens array based on wavelengths of the light, wherein the color separation lens array comprises a plurality of periodic regions in which the one or more nano-posts are repeatedly arranged, and the color separation lens array is configured to change continuously phase distribution in the plurality of periodic regions and to interrupt phase distribution at a boundary between adjacent ones of the plurality of periodic regions.
 2. The color separation element of claim 1, wherein the plurality of periodic regions comprises a first periodic region and a second periodic region adjacent to each other, and a first phase distribution formed by a first set of the one or more nano-posts of the color separation lens array in the first periodic region and a second phase distribution formed by a second set of the one or more nano-posts of the color separation lens array in the second periodic region do not overlap at the boundary between the first periodic region and the second periodic region.
 3. The color separation element of claim 1, wherein the color separation lens array in one periodic region is configured to form an asymmetrical phase distribution for each wavelength light of the incident light.
 4. The color separation element of claim 1, wherein the color separation lens array in one periodic region is configured to form a non-radial phase distribution for each wavelength light of the incident light.
 5. The color separation element of claim 1, wherein the plurality of periodic regions comprises a first region for focusing first wavelength light, a second region for focusing second wavelength light, a third region for focusing third wavelength light, and a fourth region for focusing first wavelength light, the first region and the fourth region are located on a diagonal line, and the second region and a third region are located on a diagonal line.
 6. The color separation element of claim 5, wherein the first wavelength light comprises green light, the second wavelength light comprises blue light, and the third wavelength light comprises red light.
 7. The color separation element of claim 5, wherein the first wavelength light has a phase of 2 Nπ at the center of the first region and the phase of the first wavelength light decreases in directions toward the outside of the periodic region, where N is an integer greater than
 0. 8. The color separation element of claim 7, wherein a phase of (2N−1)π is exhibited at the center of the second region, and a phase of (2N−1)π is exhibited at the center of the third region, where N is an integer greater than
 0. 9. The color separation element of claim 1, wherein the color separation lens array is configured to form a continuous phase distribution within each of the plurality of periodic regions.
 10. An image sensor comprising: an optical sensor comprising a plurality of light detecting cells for sensing light; a spacer layer provided in the optical sensor; and a color separation lens array, which comprises one or more nano-posts arranged on the spacer layer, the color separation lens array configured to form a phase distribution that splits and focuses light incident to the color separation lens array based on wavelengths of the light, wherein the color separation lens array comprises a plurality of periodic regions in which the one or more nano-posts are repeatedly arranged, and the color separation lens array is configured to change continuously phase distribution in the plurality of periodic regions and to interrupt phase distribution at the boundary of the plurality of periodic regions.
 11. The image sensor of claim 10, wherein the plurality of periodic regions comprises a first periodic region and a second periodic region adjacent to each other, and a first phase distribution formed by a first set of the one or more nano-posts of the color separation lens array in the first periodic region and a second phase distribution formed by a second set of the one or more nano-posts of the color separation lens array in the second periodic region do not overlap at the boundary between the first periodic region and the second periodic region.
 12. The image sensor of claim 10, wherein the color separation lens array in one periodic region is configured to form an asymmetrical phase distribution for each wavelength light of the incident light.
 13. The image sensor of claim 10, wherein the color separation lens array in one periodic region is configured to form a non-radial phase distribution for each wavelength light of the incident light.
 14. The image sensor of claim 10, wherein the plurality of periodic regions comprises a first region for focusing first wavelength light, a second region for focusing second wavelength light, a third region for focusing third wavelength light, and a fourth region for focusing first wavelength light, the first region and the fourth are located on a diagonal line, and the second region and a third region are located on a diagonal line.
 15. The image sensor of claim 14, wherein the first wavelength light comprises green light, the second wavelength light comprises blue light, and the third wavelength light comprises red light.
 16. The image sensor of claim 14, wherein the first wavelength light has a phase of 2 nπ at the center of the first region and the phase of the first wavelength light decrease in directions toward the outside of the periodic region, where N is an integer greater than
 0. 17. The image sensor of claim 16, wherein a phase of (2N−1)π is exhibited at the center of the second region, and a phase of (2N−1)π is exhibited at the center of the third region, where N is an integer greater than
 0. 18. The image sensor of claim 10, wherein the color separation lens array is configured to form a continuous phase distribution within each of the plurality of periodic regions.
 19. The image sensor of claim 10, further comprising a color filter between the optical sensor and the spacer layer.
 20. The image sensor of claim 10, further comprising a photographing lens unit configured to focus light reflected by an object on a light incidence side of the color separation lens array and form an optical image. 